LTC6602 Datasheet, PDF (1/28 Pages) Linear Technology – Dual Matched, High Frequency Bandpass/Lowpass Filters

LTC6602
Dual Matched, High
Frequency Bandpass/Lowpass Filters
FEATURES
DESCRIPTION
n _{Matched Dual Filter/Driver, Ideal for RFID Readers}
n _{Guaranteed Phase Matching to Within 2 Degrees}
n _{Guaranteed Gain Matching to Within 0.2dB}
n _{Configurable as Lowpass or Bandpass}
Programmable 5th Order Lowpass: 42kHz to 900kHz
Programmable 4th Order Highpass: 4.2kHz to 90kHz
n _{Programmable Gain: 1×, 4×, 16×, 32×}
n _{Simple Pin Programming or SPI Interface}
n _{Low Noise: –145dBm/Hz (Input Referred)}
n _{Low Distortion: –75dBc at 200kHz}
n _{Differential, Rail-to-Rail Inputs and Outputs}
n _{Input Range Extends from 0V to 5V}
n _{Low Voltage Operation: 2.7V to 3.6V}
n _{Shutdown Mode}
n _{4mm × 4mm QFN Package}
APPLICATIONS
n _{Multiprotocol RFID Readers:}
EPC-GEN2, ISD and IPX
n _{IDEN, PHS, GSM Basestations}
n _{Repeaters, Radio Links, and Modems}
n _{Wireless Telemetry}
n _JTRS
The LTC^®6602 is a dual, matched, programmable bandpass
or lowpass filter and differential driver. The selectivity of the
LTC6602, combined with its phase matching and dynamic
range, make it ideal for filtering in RFID systems. With two
degree phase matching between channels, the LTC6602 can
be used in applications requiring highly matched filters,
such as transceiver I and Q channels. Gain programmabil-
ity, and the fully differential inputs and outputs, simplify
implementation in most systems.
Both channels of the LTC6602 consist of a programmable
lowpass and highpass filter. For bandpass functionality,
the lowpass filters are programmed for the upper cutoff
frequency. For lowpass functionality, the highpass filters
can be bypassed. The filter cutoff frequencies can be set
with a guaranteed accuracy of 3% with the use of a single
resistor. Alternatively, the filter cutoff frequencies can be
controlled with an external clock.
The LTC6602 operates on a single 2.7V to 3.6V supply
and features a low power shutdown mode.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners..
TYPICAL APPLICATION
UHF RFID Reader Dual Baseband Filter and Dual ADC
3V
I INPUT
Q INPUT
38.3k 0.1μF
MUTE
INPUT
FROM
TRANSMITTER
0.1μF
0.1μF
100Ω
A_IN+
V+_IN
V+_A V+_D
+INA
–OUTA
–INA
+OUTA
+INB
–OUTB
–INB
+OUTB
LTC6602
R_BIAS
CLKIO
V_OCM
SER
MUTE
CLKCNTL
GAIN0(D0) HPF0(SDO)
I OUTPUT
Q OUTPUT
100Ω
100Ω
100Ω
100pF
100pF
100pF
A_IN–
14-BIT
ADC
2.2μF
V_CM
LTC2297
B_IN+
100pF
100pF
100pF
B_IN–
14-BIT
ADC
GAIN1
GND
GND
HPF1(SDI)
CLK IN
LPF0(SCLK)
6602 TA01
LPF1(CS)
CS SCLK SDI
÷4
SPI CONTROL INPUT
CLOCK INPUT
24MHz TO 128MHz
(COVERS THE TAG BACKSCATTER LINK FREQUENCY RANGE OF 40kHz to 640kHz
OF THE CLASS 1 GENERATION 2 UHF RFID COMMUNICATION PROTOCOL)
Gain vs Frequency
20
EXTERNAL CLOCK = 90MHz
10
15kHz-150kHz BPF
90kHz-900kHz BPF
0
–10
–20
–30
–40
–50 45kHz-300kHz BPF
–60
1k
10k
100k
1M
FREQUENCY (Hz)
10M
6602 TA01b
6602fa
1